Inductor for induction heating of objects of various sizes and shapes



Oct. 7, 1947. FlNGER 2,428,705

INDUCTOR FOR INDUCTION HEATING OF OBJECTS OF VARIOUS SIZES AND SHAPES Filed Sept. 6, 1945 2 Sheets-Sheet l //V VE N TOR ARM/N A.FINGER AIIMQ M ATTORNE Y Oct. 7, 1947.

FIN R 2,428,705 INDUCTOR FOR I UCTlON TING OF OBJECTS OF VARI SIZES AND SHAPES Fi Sept. 6, 1945 2 Sheets-Sheet 2 6' 7 /0 v .1 I I n }MPM% /NVENTOR 1 ARM/NAF/NGER AW M, Qui l-M ATTORNEY Patented Oct. 7, 1947 INDUCTOR FOR INDUCTION HEATING OF OBJECTS OF VARIOUS SIZES AND SHAPES Armin A. Finger, Bronx, N. Y., assignor to Induction Heating Corp, New York, N. Y., a corporation of New York Application September 6, 1945, Serial No. 614,635

4 Claims.

This invention pertains to improvements in high frequency induction heating apparatus. More particularly, the invention provides an apparatus of this character adapted to heat treat efficiently any of a number of preselected objects having different sizes and shapes, but without the necessity for changing electrical connections from the high frequency supply source or disconnecting the Water or cooling fluid conduits, in changing from one type of such object to be heated to another, while at the same time providing, in each instance, a heating unit conforming closely in size and shape to the object to be heated, irrespective of the particular object selected from the group for which the apparatus is designed.

In accordance with the invention, I propose to accomplish the results aforesaid by means of a construction employing, in its preferred embodiment, a master energizing. coil of an annular, split-ring construction, and a heat treating unit consisting of a relatively large metal insert plate of circular contour fitting within the master coil and detachably secured thereto, the master coil and the insert being made of a suitable low-loss material, such as copper. The plate or insert is provided with a plurality of apertures extending transversely therethrough and each conforming in size and shape, both peripherally and sectionally, to the size and shape of a particular object or portion thereof to be heat treated. From each such aperture, a slot extends radially to the periphery of the insert. About its periphery, the insert is provided with a projecting flange. and abutting shoulder for mounting the same on the master coil, the latter being provided, for this purpose, and about its inner periphery, with a complementary flange and abutting shoulder. The master coil which thus takes the form of an annular frame supporting the insert, is provided with a single slot extending transversely, i. e., radially therethrough thereby providing a splitring arrangement. From the opposite sides of this slot, electrical connections extend respective-- ly to the respective terminals of a high frequency supply source. The electrical connections and themaster coil include a passageway for circulation of water or other cooling fluid, which passageway extends fromone electrical connection aforesaid around the interior oi'the master coil to the opposite electrical connection.

The flanged portion of the master coil is bolted or otherwise detachably and adjustably fastened to the flanged portion of the insert in such manher that by removing or loosening the fastening means, the insert may be. rotated with respect to the master coil, thereby to align any preselected slot in the insert with the slot in the coil. In consequence, high frequency current supplied to the coil over the connections aforesaid, will be concentrated about the insert aperture, the slot of which is aligned with the slot in the master coil, since this provides the path of minimum reactance between the electrical connections supplying high frequency energy to the master coil and insert. This construction accordingly provides optimum heating of and close inductive coupling to an object of configuration corresponding to the aforesaid insert aperture upon insertion of such object therein.

If now it is desired eificiently to heat treat an object of a different shape corresponding to another aperture in the metal plate, it is required only to remove or loosen the fastening means between the master coil and insert, and to rotate the insert until the slot adjoining the desired aperture therein is aligned with the slot in the master coil. Thus, the high frequency energy supplied to the coil connectors will now be concentrated about this newly aligned insert aperture, whereby optimum heating is effected upon an object of shape conforming thereto, inserted therein.

It will be understood that the insert need not be of circular and the master coil of annular configuration. For example, both may be of rectangular, polygonal or other contour, and arranged fo-r slot alignment by relative rotation or slidable adjustment of the insert with respect to the coil, without departing from the spirit of the invention.

In the drawings:

Fig. 1 is a plan view of the aforesaid preferred embodiment of the invention employing the circular insert and annular split-ring master coil; while Figs. 2 to 6 inc. are sections respectively at 22 to 6-6 inc. of Fig. 1, Fig. 2 being modified by the insertion in the aligned aperture, of an object of conforming shape to be heat treated.

Referring to the drawings, the insert, which takes the form of a. circular plate comprising the heating unit, is shown generally at I, and the split-ring master coil at 2. The insert l is provided with a plurality of apertures 3 to W inc., extending transversely or axially therethrough. As shown, by reference to the plan view, Fig. l, as well as to the sectional views, Figs. 2 to 6 inc., each aperture 3 to Hi inc. conforms in size and shape, both peripherally and sectionally, to the size an shape of a particular obj t to e h t as indicated, for example, by the object Ila, Fig. 2, inserted in aperture 3.

From each aperture 3 to ID inc., a radial slot, such as II, I2, I3, extends to the periphery of insert i. Also, a single slot I4 extends transversely or radially through the master coil 2 to provide, in effect, a split-ring induction heating loop, which is energized with high frequency current by means of a pair of bus bars I5, I8, extending respectively from the terminals IT, IS of the usual high frequency supply transformer I9, to portions of the master coil 2 forming the opposite sides of slot I4 therein. The connections comprising bus bars I5, I6 and the transformer terminals I'I, I8 respectively connected thereto are insulated from one another by means including an insulating gap 20, constituting a continuation of the gap or slot I I in the master coil.

For cooling the master coil and insert and other contiguous parts, during high frequency energization thereof, coil 2 is provided with an internal passageway 'ZI extending thereabout. This passageway communicates at its opposite ends, adjacent slot 14, in conduits 22, 23 formed in or integral with and extending along the bus bars I5, It to a point adjacent the transformer I9, where the conduits pass ofi at right angles to a source of cooling fluid, such as water, etc.

Insert terminates, about its periphery, in a projecting flange 24, Fig. 3, and abutting shoulder for centering and supporting the same within the aperture of coil 2, the latter being provided about its inner periphery, for this purpose, with complementary projecting flange 263 and abutting shoulder portion 21.

For detachably and adjustably securing the insert to the coil, the overlapping flanged portions 26, 28 thereof are drilled at equal angular intervals for reception of fastening means comprising bolts and nuts 28, 29, Figs. 1 and 3. As shown in Fig. 1, the angular spacings between adjacent bolts 28 correspond to the angular spacings between adjacent radial slots, such as Ii, in plate l, whereby the holes for the bolts are such as to permit of aligning any of the insert slots, such as II, I2, I3, etc., with the slot IG- in the master coil. Thus, for example, with the insert attached to the master coil as shown in Fig. 1, insert slot I2 adjoining insert aperture 3, is aligned with the master coil slot I4. By removing the bolts 28 and rotating insert I with respect to coil 2, any other insert slot, such as I! or I8, joining any other insert aperture, such as i or iii, may be similarly aligned with the coil aperture I i. More simplified slot-aligning means may be employed, such as cooperating dowel pins and holes provided in the insert and coil respectively, whereby any desired slot alignment may be quickly secured by merely lifting and rotating the insert, for which purpose any suitable standard type of lifting and rotating mechanism may be provided.

Referring now to the operation of the apparatus, assume that it is desired to heat treat an object of a particular shape, such as Ha, conforming in size and configuration to one f the insert apertures, such as the insert I is adjusted as aforesaid in relation to coil 2 until the insert slot I2, communicating with the selected insert aperture 3, is in alignment with the coil slot i i. The object lid is now inserted in aperture the circulation of cooling fluid initiated in passageways 2|, 22, 23, and the power supply transformer I9 energized. The resulting high frequency current supplied over bus bars I5, I6 will flow principally in the portions of the master coil 2, which are adjacent to slot I4 therein, and also will be concentrated in the portions of insert I which closely surround the aligned slot I2 and adjoining aperture 3, since this provides the path of minimum reactance between the bus bars. Thus, the induction heating currents will be concentrated about the aligned insert aperture, such as 3, containing the object, such as IIa, being heat treated, and since this object conforms closely in size and shape to the appropriate heating aperture in which it is inserted, close inductive coupling will be provided between the object and the insert, whereby optimum, efficient heating is obtained.

It will be observed that with the construction described, changes from one shape of object to be heat treated to another involve no corresponding changes in the electrical or cooling fluid connections to the master coil 2.

I claim:

1. High frequency induction heating apparatus, comprising: an induction heating coil of splitring configuration containing a slot, electrical connections extending to said coil on opposite sides of said slot, respectively, for supplying high frequency current thereto; a conductive insert spanning the aperture of and supported by said coil, said in ert containing a plurality of angularly displaced apertures, each for conforming closely to the size and shape of an object to be heated, a slot extending from each such aperture to the periphery of said insert; and means adjustably securing said insert to said coil, whereby any slot aforesaid of said insert may be aligned with the slot in said coil, thereby to concentrate high frequency induction currents about the adjoining aperture of said insert.

2. High frequency induction heating apparatus, comprising: an induction heating coil of split-ring configuration containing a slot; electrical connections extending to said coil on opposite sides of said slot, respectively, for supplying high frequency current thereto; said connections and said coil including a cooling fluid passageway extending about the interior of the coil; a plate-like, conductive insert supported about its periphery by said coil; said insert containing a plurality of angularly displaced apertures, each for conforming closely to the size and shape of an object to be heated; a slot extending from each such aperture to the periphery of said insert; and means adjustably securing said insert to said coil, whereby any slot aforesaid of said insert may be aligned with said slot in said coil, thereby to concentrate high frequency induction heating currents about the adjoining aperture of said insert.

3. High frequency induction heating apparatus, comprising: an induction heating coil of splitring construction containing a slot and having a supporting flange and abutting shoulder about its inner periphery; electrical connections extending to said coil on opposite sides of said slot, respectively, for supplying high frequenc current thereto; said connections and coil including a cooling fluid passageway extending from one said connection about the interior of the coil to the remaining said connection; a plate-like, circular insert spanning the aperture of said coil, and provided about its periphery with a flanged extension and abutting shoulder complementary to those of said coil for support thereon in heat and electrical conducting relation; said insert containing a plurality of angularly displaced apertures, each for conforming closely in size and contour to a portion of an object to be heated; a slot extending from each said aperture to the periphery of said insert; and means detachably and adjustably securing said insert to said coil, whereby any preselected slot of said insert may be aligned with said slot of said coil, thereby to concentrate electrical heating currents supplied from said coil about the adjoining aperture of said insert to heat an object inserted therein.

4. High frequency induction heating apparatus, comprising: a plate-like heating unit of conductive material containing a plurality of spaced apertures, each for conforming in size and contour to the size and shape of an object to be heated upon insertion in said aperture; a slot extending from each aperture to the periphery of said heating unit; a conductive frame supporting said heating unit along its periphery; said frame having a slot extending transversely therethrough; electrical connections extending to said frame on each side of said frame slot, respectively, for

supplying high frequency current; and means adjustably securing said heating unit to said frame for aligning the slot in said frame with any preselected slot of said heating unit, thereby to concentrate about the adjoining aperture of said heating unit, high frequency currents supplied from said electrical connections.

ARMIN A. FINGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,271,916 Denneen et a1. Feb. 3, 1942 2,353,130 Dravneek July 11, 1944 OTHER REFERENCES Roberds, Coupling Methods for Induction Heating, Electronic Industries, April 1944, pages 180, 182. 

